Musnad Ahmad Hadith 771

I heard a man praying for forgiveness for his parents, who were mushrikeen. I said: Would a man pray for forgiveness for his parents when they are mushrikeen? He said: Didn`t Ibrahim (عليه السلام) pray for forgiveness for his father? I mentioned that to the Prophet (ﷺ) and the words `It is not proper for the Prophet (ﷺ) and those who believe to ask Allah`s forgiveness for the Mushrikoon, even though they be of kin, after it has become clear to them that they are the dwellers of the Fire (because they died in a state of disbelief). And Ibrahim`s (Abraham) (عليه السلام) invoking (of Allah) for his father`s forgiveness was only because of a promise he [Ibrahim (Abraham]] had made to him (his father). But when it became clear to him that he (his father) is an enemy of Allah, he dissociated himself from him” At- Tawbah [9:113-114] were revealed. He [the Prophet (ﷺ) ] said: `[That was] when he died.`